Wits end with misfire.
 

Just did a valve job on an 09 r56 and the problems just dont seem to end. The thermostat developed a crack, and throttle body was returning a code for weak return spring. I seem to have these issues sorted out but I have a persistent misfire on #4. I have eliminated the coils, plugs and injectors as a possibility. Compression seems to be in line with the others. Leakdown is perfect. I checked the wiring from the DME to the coils and the injectors and it seems fine. I tried to test the injectors with a noid light but I can only access #4, and I'm not sure I'm testing it correctly. It was fine when cold and only started misfiring when the temp got to about 200, but now it misfires all the time. I'm using Bavarian Tech diagnostics. Has anybody ever seen anything like this before? Is there anything else I can test?